1. Field of the Invention
The present invention relates to the field of positron emission tomography (PET). More particularly, this invention relates to a system and method for manually loading and remotely unloading a target disk into a proton beam.
2. Description of the Related Art
Accelerators are commonly used to produce radionuclides for a variety of uses including Positron Emission Tomography (PET). PET is a noninvasive diagnostic imaging procedure that assesses the level of metabolic, biochemical, and functional activity and perfusion in various organ systems of the human body. PET provides information not available from traditional imaging technologies, such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) which depict changes in anatomy rather than changes in physiology. Physiological activity provides a much earlier detection measure for certain forms of disease, cancer in particular, than do anatomical changes over time.
Typically, an accelerator produces radionuclides by accelerating a particle beam and bombarding a target material with the accelerated beam thereby producing radionuclides. The type of radionuclides produced are determined by the target material and particle beam used.
Low or medium energy charged-particle accelerators typically produce radionuclides having a short half life. Radionuclides such as copper-64 or 64Cu have a longer half life than the conventional radionuclides typically used. Specifically, copper-64 is the cyclotron-produced PET isotope of copper. This isotope undergoes a special type of radioactive decay, whereby its nuclei emit positrons that travel only a few millimeters in tissue before colliding with electrons, converting their total mass into two photons of energy. The photons are displaced at 180 degrees from each other and can be detected simultaneously as “coincident” photons on opposite sides of the body.
However, copper-64 is not easily producible as is shown in U.S. Pat. No. 6,011,825 which is incorporated herein in its entirety by reference. The production of copper-64 requires the irradiation of a solid target rather than a liquid or gaseous target that conventional accelerators are capable of handling.
The combination of gold with plated enriched nickel can be used to produce copper-64. Other combinations of metals can also be used to provide copper-64. In addition, the combination of metals can take the form of pellets, foil or coin.
There is a need for a target holder for loading and unloading a solid target to produce a radionuclide.
There is also a need for a target holder that can accommodate a solid as well as a liquid and gas target cost effectively.
There is a further need for a target holder that has a service position and an irradiation position